Process of preparing material for use in making up repairing, and replacing linings, &amp;c., of metallurgical furnaces.



UNITED I STATES rATEnT OFFICE.

JOHN E. BAKER, OF YORK, PENNSYIIVANIA.

. Pnocnss or PREPARING MATERIAL FoaUsE IN MAKING Ur REP IRING, Ann

REPLACING LININGS, &o., F METALLURGICAL roanncns.

1,063,103. No Drawing.

To all whom it mayconoern Be it known'that- I, Jenn E. BAKER, a citizen of the United States, residing at York, in the county of York and State of Pennsylvania, have invented certain new and useful Impr-zrrements in Processes of Preparing Material for Use in Making Up, Repairing, and Replacing Linings, &c., of Metallurgical Furnaces, of which the following is a specification.

This invention relates to an improvement in the process of preparing material for use in making up, repairing and replacing linings, bottoms and parts; of metallurgical furnaces.

In the operation of metallurgical furnaces, especially those known as open hearth furnaces, itis found that tbe'linings thereof soon deteriorate and are destroyed at points adjacent the slag line or upper surface/of the material being treated and also at various points in the bot-toms thereof. It is a constant requirement on the part of the attendants to repair said damaged portions of the linings and bottoms of the furnaces and it has been ascertained that the repairs can be readily made while the fur- I nace walls are in a heated condition by the application to the damaged parts of dolomite. Dolomite in its raw state, thatis, as it comes from the quarry and after being crushed, has been used heretofore-but has been ascertained to be objectionable for various causes well known to those skilled in the art. It has therefore been attempted heretofore to supply this material in a condition where-the same is relieved largely of the contained volatile matter, gases, and etc. This has been accomplished by first roasting the dolomite and then reducing it to the proper size and such a product has beenv made heretofore by me in large quantities and then supplied to the trade. In the treatment of the dolomite under the heretofore practised method, the material has been laced in a cupola furnace, the furnace bemg charged with alternate layers of coke generated drives oil the carbonic acid gas l proximately :1 five-eighths or threeourths and raw crushed dolomite rock. The heat and other volatile constituents to a great extent and the material is taken from the eupola furnace and reduced to the prop? granulated form, such-granulated form ing usually of a size to pass throu h ap- Specification of Letters Patent.

Application filed December 6, 1911.

Patented May 27, 1913. Serial No. 664,303.

of an inch opening or'meshed screen. The product as thus produced had a number of objectionable characteristics, some of which may be mentioned as impairment, owing to the presence of fine or powdered material, coke, cinder, ash and a small percentage of volatiles. The productthus obtained was furthermore not of a uniform character,-

as so treated, it was found that some of the improperly burned fine materials would escape through and into the checker work of the open hearth furnace and tend to destroy the brick of the checker work. Manufacturers therefore objected to the use of material containing not only volatiles, but also time improperly burned materials.

In the practice of this art, I have endeavored to avoid these various objections by the employment of what is Well known as the rotary style of roasting kiln. I have found that the rotary kiln process of treating dolomite is useful in many particulars, but it is impossible to treat the granular material thereby so as to relieve it of all the moisture and "olatiles contained therein and at the same time to cause it to retain its best condition for sufficient length of time to render the product practical for all purposes. Furthermore, when it is attempted to remove. the volatile matters from crushed raw dolomite by the rotary kiln process, the resultant roduct is very light and has been found or this reason to be more or less. unsatisfactory. While, therefore, the rotary kiln method resulted in a product free from cinder or ash, yet, owing to the reasons above pointed out, the product produced thereby was not entirely satisfactory.

In the practice heretofore employed, the

marketable material has been found to be of such a character as to very readily and quickly absorb moisture, no that during the shipment of. the maferhl 'fro n 10 to 15% of nmisture would be absorbed before the all of the objections heretofore suggested have been overcome, and that I am able to produce a material of substantially'uniform character which is rendered free from foreign substances; properly burned so that practically all objectionable volatiles are driven off; and so constituted that but a. relatively small percentage of moisture will be absorbed thereby for a period of time well within the time required for shipment to remote parts of the country and well within the time between shipment and date of use. I have also found that by the present process I am able to produce a material which is much heavier, volume for volume, than any manufactured dolomiteheretofore produced, thus rendering the product available for purposes for which it has heretofore been thought impossible to use dolomite.

With the above in view, -I practice the fol lowing process :--First crush the raw dolomite into lumps approximately two to four inches in diameter; charge the same into a cupola furnace of any approved type, alternating with layers of coke; firing .the furnace; and then withdrawing the burned dolomite at intervals as in the old practice. I thereafter crush the burnt dolomite with such coke or cinder as may have remained, in a suitable apparatus and screen the same through a screen of approximately fiveeighths to three-fourths inches mesh. The raw dolomite is subjected in the cupola to a heat approximately 2800 F., from two to four hours and I find that as a result of subjecting the lumps of dolomite to this heat, they are shrunk or condensed to a marked degree, so much so that dolomite burned in the cupola in this manner will weigh considerable more than an equal volume of raw unburned dolomite notwithstanding the fact that much of the volatile matter has been expelled from the raw dolomite. The product thus produced has mixed with it a material percentage of ash, coke, and fine'or dust material (the latter being objectionable in furnace practice). The material is also manifestly unequally burned owing to the fact that the size of the rock introduced into the furnace is required to be sufficient to permit the proper draft through the furnace, and therefore the interiors of these large masses ofrock have been found to be improperly burned and to contain volatiles objectionable for the reasons heretofore stated. The crushed product with the objectionable materials and characteristics, I then preferably, without further treatment, subject to a second burning, conveniently by introducing the same directly into a rotary kiln, and by further subjecting the said,

product to a degree of heat approximately 2400 F., the coke and cinder constituents ofthe mass are consumed, and the finer particles of dust are either fused or carried over into the up-take or otherwise eliminated 1 therein. In addition to relieving the granulated mass of the cinder, carbon and fine objectionable particles, by this proeess, I have also ascertained that the various granules which have been subjected to the burning action in the rotary kiln are rendered much less pervious 'to moisture than heretofore.

This I attribute in a great measure to the fact that when thegranules are burned in the rotary kiln, they are further shrunk or condensed, and I have found that the material after being treated in the rotary kiln in the manner above described, will volume for volume weigh considerably more than either the raw dolomitestone or the dolomite after it has been roasted in the cupola. In fact, the material which is obtained from the rotary kiln is substantially volume for volume, is much heavier than the material obtained from the cupola, as the material obtained from the cupola is heavier than the raw dolomite, and the product which is obtained in this manner .is almost twice as heavy, volume for volume, as the product which is obtained when it is endeavored to roast granulated dolomite in accordance with the rotary process. also found to be substantially uniform in its physical characteristics.

The fact that the material obtained by the present process is for a considerable period of time substantially impervious to moisture, may he also due in some measure to the presence of a small percentage of sili cious'materials contained in the coke which has been passed into the kiln with the roasted dolomite, and also to the fact that coke has been used in the cupola under the first step of the treatment. lVhile I have not ascertaihed definitely the cause of this particular action, from which the beneficial results are obtained, I have found that the product will not, for a considerable time, absorb any appreciable amount of moisture. In fact, I have found that shipments of this material can be delivered hundreds of miles distant and that for a period of twentydive or thirty days, the material will have absorbed no objectionable amount of The product is moisture. I am therefore able to supply the I steel works with a material which-1s insub stan'tially perfect condition .for use, and, in fact, in a condition which. has heretofore been commercially impossible. This will be apparent when it is understood that dolovmite quarries are not ordinarily located in the immediate vicinities of steel works.

' As a replacing and repairing material dolomite, in the condition which I am now able to produce and supply the same, is important from ,a standpoint of economy on behalf of steel manufacturers, but I wish itunderstood that the material produced by the present method may be employed forpurposes other. than that of repairing the slag line ofthe furnaces- In fact, thematerlal can be used withgood results owing .to its dense character, for closing the tap holes in furnaces and also for building up furnace bottoms. This is very important asit enables the useof my substantiallyperfectly prepared dolomite for purposes in connection with which dolomite'hasheretm fore been found impractical,- and forwhich purposes it has been necessary to-use magne site which must be imported and is very expensive. 3 i

The granules of the completed product, as far as I have been ableto ascertain, are substantially uniform in characteriand they have a slightly silicious and dense outer surface part, and to distinguish the-material from that produced separately by either the;

cupola or rotary kiln processes, the same may be characterized as double burned dolomite.

I wish it to be understood that the method is not limited tothe use of any particular apparatus and that the steps thereof may be somewhat varied without departing from the nature and principle of the invention. Vha't I claim is 1. The method of producing a dolomite mater1al for repairing furnace lin ngs and the like, consisting in burning raw dolomite rock, breaking the burned rock, and subsequently reburning the broken rock'to produce a'uniforni product.

2. The method of. producing a dolomite material for repairing furnace linings and. the like conslstlng 1n first burning the rawrock in cupola furnace, breaking the burned rock, and finally. reburning the. broken'rock,

3. The method of producing dolomite material for repairing furnace linings and the like consisting in first burning the raw rock in a cupola furnace, breaking the burned in a rotary kiln.

rock, and finally reburning the brokenrock- 4. The method of producing a dolomite r material for'repairing furnace linings and the like consisting in burning raw dolomite rock, breaking, and subsequently reburning the burned rock by subjecting the same to a-high degree of heat uniformly burning the various particles of the mass.

5. The method of producing a dolomite material for repairing .furnace -.linings and the like consisting in burning raw dolomite rock, granulating the same and subsequently re'burning the burnt. rock in granular. form. 6. The method. of producing a dolomite material for repairing furnace linings and the like consisting in burning raw dolomite. rock .in the presence of a carbon fuel, break- 8. The method of producing a dolomite material for repairing furnace'linings and the like consisting in burning. raw dolomite in the presence of a combustible, reducing the burned rock, and subjecting the reduced material while in a free state to the action of heat to relieve the. product of obj ectionable materials and to reburn the dolo- 9."The method of producing a dolomite, material for repairing furnace linings andthe like consisting in burning raw dolomite by subjecting the raw stone to a'heatof approximately 2800 F., breaking the rock into granules, and subjecting such granules to an intense heat.

1'0. The method material for repairing furnace linings consisting in first subjecting the raw rock td a heat sufficient to drive off the volatile mattors therefrom and condense the rock, breaking the rock so treated int-o granules, and- 's'ubjec-tingthe granules to intense heat to further condense the same.

of producing dolomite In testimony whereof I, afiix'my signature in presence of two witnesses.

WVitnesses:

S.- D. WAREHEIM, FREDERICK B. German.

JOHN E. BAKER.- 

